The present invention relates to a method and an arrangement for radio telecommunication such as telephony, video, audio and/or high rate data and interactive data communication via a cable television network.
Telecommunication services are, for the greater part, bounded to dedicated networks. Speech communication is mainly provided by the Public Switch Telephony Network (PSTN). Video and audio communication is handled by Cable TeleVision (CaTV) networks, and high rate data communication is exchanged over distinct data networks, for example. This results, at the users"" site, in as many as access provisions as the number of networks of which a user requires services.
With the increase of telecommunication services applied by a user, a trend to integration or convergence of services can be envisaged. Computer Integrated Telephony (CIT) is an example of the integration of telephony and data services, where video conferencing is the result of the integration of telephony and video communications. Service integration at the operators"" site will inevitably lead to integrated workstations for video, telephony, data communications etc. at the users"" premises.
In a next step, integration at the network level will take place for which standards like Asynchronous Transfer Mode (ATM) are currently under construction. Internet can be regarded as a first introduction of an integrated or converged network with which from an integrated (multi-media) workstation over an integrated network (Internet) a number of the above distinct services are available. However, it is yet still not clear at which point in time a final integrated network will be available to the majority of telecommunication users.
In the meantime there is a need for a cost effective and quickly to implement solution to provide the best possible integration of telecommunication services on existing networks.
It is an object of the present invention to provide a solution for an integral provision of telecommunication services such as speech or telephony, video, audio, high rate data and interactive data communications.
It is a further object of the present invention to provide an integrated services network terminal unit for use at the subscriber or user premises.
According to the present invention there is provided an arrangement for integrated telecommunication via a Cable TeleVision (CaTV) network in a first or downstream direction from a first or head-end section to second or subscriber sections and in a second or upstream direction from the second or subscriber sections to the first or head-end section, through intermediate trunk, distribution, district, feeder and drop sections, intermediate trunk units connecting the trunk and distribution sections, and distribution and/or district centers connecting the distribution and district sections, and first communication means operative through the CaTV network at a low-end frequency sub-band thereof in accordance with the Digital Enhanced Cordless Telecommunications (DECT) standard, characterized in that the first communication means comprise a plurality of radio access units arranged at the distribution and/or district centers for communication with the subscriber sections through the district, feeder and drop sections of the CaTV network, and wherein the subscriber sections comprise Network Terminal Unit (NTU) means arranged for up-converting to the DECT standard frequency band of the low-end frequency sub-band DECT signals for radio transmission by the NTU means to provide wireless radio communication at the subscriber sections, and for down-converting to DECT signals for transmission at the low-end frequency sub-band in the CaTV network of signals at-the DECT standard frequency band received by the NTU means from wireless radio communication at the subscriber sections.
A typical CaTV network comprises a so-called head-end station equipped with receiver means for receiving signals transmitted by terrestrial satellite transmitters and other communication service providers. The received signals are frequency converted and transmitted by coaxial and/or optical cable via a trunk network and various distribution or district sections and intermediate trunk and distribution and/or district centers to individual CaTV subscriber terminals in the subscriber""s homes. The trunk network serves to bridge relatively long distances between a head-end station and the various district sections. From the district sections a drop section serves the subscriber terminals through feeder cables and intermediate tap and amplifier units.
International patent application WO 95/34168 and European patent application 0,695,092 disclose simplified versions of CaTV and coax/fiber cable networks, wherein radio and TV signals and control and telephone data are transmitted from the head-end section to the individual subscribers. Downstream and upstream duplex channels occupy different frequency bands of the network, including the low-end CaTV frequency sub-band.
From a network reliability point of view, in case of a power supply failure, two-way communication (i.e. in the up-downstream directions) at the distribution, district, feeder and drop sections is only readily possible in the low-end CaTV frequency sub-band. However, this sub-band is susceptible for noise and other interferences.
Digital Enhanced Cordless Telecommunications (DECT) is a low power, high capacity Multi Carrier/Time Division Multiple Access/Time Division Duplex (MC/TDMA/TDD) digital radio access technique, providing ten radio carriers, each divided into 24 time-slots which serve 12 duplex 32 kb/s communication channels, called a frame. The 120 communication channels are continuously adaptively selected. A communication channel, when occupied, is individual to a radio link connection between a radio access station an a particular remote telecommunication unit, such as a cordless radio telephone. This type of access technique is known as Continuous Dynamic Channel Allocation (CDCA). The DECT protocol provides data exchange at rates of 32 kb/s or less up to 552 kb/s or more.
An elaborated discussion on DECT can be found in a paper by D. xc3x85kerberg, xe2x80x9cNovel Radio Access Principles Useful for the Third Generation Mobile Radio Systemsxe2x80x9d, The Third IEEE International Symposium on Personal, Indoor and Mobile Radio Communication, Boston Massachusetts, Oct. 19-21, 1992, which paper is included here by reference.
The present invention is based on the insight that by providing the radio access units at the distribution and/or district centers, to each distribution or district section connecting to a distribution and/or district center the full 120 DECT communication channels are available. This different from radio access units installed at the head-end, which allows only 120 channels per CaTV network.
Those skilled in the art will appreciate that, instead of installing the radio access unit at the distribution and/or district centers, installation at the trunk units is also feasible, this dependent on the capacity required.
With the arrangement according to the invention, at the subscriber sections, wireless radio communication is provided, wherein subscribers having a mobile radio terminal can communicate in their neighbourhood via a connection with their own NTU and/or a neighbouring NTU. In case of NTU""s connected to the same radio network, no complex roaming or handovers are required.
The NTU""s preferably comprise DECT repeater units, which may connect over air to Fixed Access Units (FAU) in the home. These FAU may be provided with identity and access rights, such that the NTU""s can be relatively ill equipped, merely serving as a conversion means, and NTU""s at low costs can be provided.
The present invention further combines the advantages of the existing CaTV networks, i.e. high rate data capacity in downstream direction and a relatively low data rate capacity in the upstream direction by an arrangement further comprising second communication means operative in accordance with a second transmission protocol serving at least downstream communication at high data rates, and third communication means connected to said first and second communication means and serving at least downstream communication at high data rates and upstream communication at DECT based data rates through said first communication means.
The present invention is based on the insight that the majority of users, such as Internet users for example, generate relatively little traffic in the direction of the host or data source from which data are required (i.e. in the upstream direction of the CaTV network). The main data stream is in the direction of the users (i.e. in the downstream direction of the CaTV network). By combining, according to the present invention, a telephony based communication service operating at the CaTV network and the upstream communication requirements of a high data rate user, a very efficient use of the spectrum or frequency resources of a CaTV network is achieved.
In the preferred embodiment of the invention the second transmission protocol is operative at a video frequency band of the CaTV network. With this embodiment of the invention, there is no need for modifications of the existing CaTV transmission infrastructures.
The second transmission protocol may be chosen from among existing analogue or digital radio communication protocols for high data rate exchange, in particular a Time Division Multiple Access (TDMA) radio communication protocol. In a preferred embodiment of the invention high data rate exchange is provided over one or more 5 MHz bandwidth video channels of the CaTV network. Using the so-called 64 QAM modulation technique, data at 34 Mb/s can be exchanged over such as channel.
The invention relates also to a method of integrated telecommunication via a Cable TeleVision (CaTV) network in a first or downstream direction from a first or head-end section to second or subscriber sections and in a second or upstream direction from the second or subscriber sections to the first or head-end section, through intermediate trunk, distribution, district, feeder and drop sections, intermediate trunk units connecting the trunk and distribution sections, and distribution and/or district centers connecting the distribution and district sections, wherein communication is served through the CaTV network at a low-end frequency sub-band thereof in accordance with the Digital Enhanced Cordless Telecommunications (DECT) standard, characterized by the steps of serving upstream and downstream DECT communication at a low-end frequency sub-band of the district, feeder, and drop sections of the CaTV network, at the subscriber sections, up-converting to the DECT standard frequency band of the low-end frequency sub-band DECT signals by Network Terminal Unit (NTU) means and radio transmission of the up-converted DECT signals by the NTU means for providing wireless radio communication at the subscriber sections, and at the subscriber sections down-converting to DECT signals at the low-end frequency sub-band of the CaTV network and transmission thereof through the drop, feeder and district sections to the radio access units of signals at the DECT standard frequency band received by the NTU means.
The invention further provides a subscriber Network Terminal Unit (NTU) for use in an arrangement disclosed above, comprising first communication means operative in accordance with the Digital Enhanced Cordless Radio Telecommunications (DECT) standard, characterized by conversion means for up-converting to the DECT standard frequency band of DECT signals at a low-end frequency sub-band of a Cable TeleVision (CaTV) network for radio transmission by the NTU means for providing wireless radio communication at subscriber sections of the CaTV network and for down-converting to DECT signals for transmission at the low-end frequency sub-band in the CaTV network of signals at the DECT standard frequency band received by the NTU means from wireless radio communication at subscriber sections of the CaTV network.
The above-mentioned and other features and advantageous of the invention are illustrated in the following description with reference to the enclosed drawings.